The morphology of salt crystals affects the perception of saltiness

- Salt crystals with different morphologies have different dissolution rate.
- High dissolution rate is correlated with high saltiness perception.
- Non-cubic and agglomerated crystals are dissolved faster.
- Internal cracks and cavities allow crystal disintegration in saliva.
- The crystal disintegration increases the dissolution rate.

High intake of salt (NaCl) has been associated with risk of non-communicable diseases, including hypertension, cardiovascular disease and stroke. Several strategies for reducing salt in foods are under study, including the relation of crystal morphology on dissolution properties of salt in the mouth. The aim of this paper was to study the dissolution of salt crystals with different morphologies in artificial saliva and to correlate the findings with the perception of saltiness over time. The morphology of five commercial salts was analyzed by scanning electronic microscopy and micro-CT studies. Shape parameters of crystals were determined using images from an optical microscope. Crystal dissolution in artificial saliva was evaluated using video-microscopy and the perception of saltiness was evaluated using sensorial test of time-intensity at standardized sodium content. Salt morphology was correlated well with dissolution rate and certain time-intensity parameters (time to maximum intensity, intensity at maximum and increase angle). Non-cubic and agglomerated crystals, such as Kosher and Maldon salts, were dissolved faster (dissolution rate up to 3.8 times higher) and experienced maximum saltiness (up to 17% more) at shorter times (up to 40% less). Crystal morphology may be a variable to consider to achieve sodium reduction while maintaining salt intensity.